Systems for interbody fusion of adjacent bone portions may include an expanding implant (100) and related instruments. An expanding implant may be formed as a linkage which is movable between a compact configuration and an expanded configuration. A shaft (110) of the implant may increase and decrease in length to move between the compact and expanded configurations, and an implant width perpendicular to the length may be increased in the expanded configuration. The implant width may increase more in a first direction than a second direction opposite the first direction. An inserter instrument may releasably grasp the spacer and transform the implant between the compact and expanded configurations.